5-Series (E12,E28, E34, E39, E60)Chat relating to the BMW 5-Series of all generations. Specific models include: BMW 518, BMW 520, BMW 520i, BMW 530i, BMW 528i, BMW 530i, BMW 518i, BMW 524d, BMW 525i, BMW 525e, BMW 528e, BMW 540i, BMW 535i, BMW 520d, BMW 525td, BMW 525d, BMW 530d, BMW 525i/xi, BMW 530i/xi. (BMW 5-Series Forum)
DEAR Mnguyen1111 on Oct 23 2004 we covered the very same question below in case if you have missed it:
QUOTE(billB @ Oct 23 2004, 03:32 PM)
you car is identical to mine. My thought will be to start a process of troubleshooting in step by step fashion...no guess work!
So the following will assume your radiator is filled/bleed properly. Just to make sure.
1. With engine running turn your AC on. Do you see/hear the electrical fan running? This fan has 3 speeds (low to highest) kicks in to keeps temp in the middle plus whenever you turn the AC compressor on. You can not miss the 3rd speed-- Loud and strong. No sound. Start with the fuses (glove box) relays (trunk above battery) temp. sensors etc then the fan itself. possible to hot wire it for testing; $300 piece of equipment.
Note: the harness "plastic connector" for this fan sits on the left side of the fan in the bumper (you can trace it starting at the black wiring in the fan itself) I have seen it melting from excessive heat. Check it out.
2. Fan clutch on the belt driven one. Although I won't go too crazy on this one.
3. Thermostat check. I doubt it though (your problem starts when the AC is on) but I would replace it either way cheap enough and winter is coming!
4. Water pumps are made of plastic guts; they do fail very often
5. Next step??? Well when you done with the above let us know how you make out. Warning this next step will be more costly...and I hope not and that is head gasket/head problems.
wish you the best of luck
thanks for your help.
Actually i don't have the AC on it is doing the same thing.
Even when I just drive the car for a few minutes after stop and go traffic.
When I turn on the engine, I see that the fan spin right away.
Therefore I believe the fan is work properly.
I took it out to Autozone and talk with someone I've spoke to a few times.
He said 90% it is the thermostat. He said there is pressure in the hose,
so when my car is stop the thermostat does not open and when I drive it ;
the pressure increase in the hose and force the thermostat to open so it cool
I am thinking about taking out the thermostat and submerge it in a boil contain.
let me know if you have others
In the old days, you took the thermostat out and put it in a boiling container to see if it open and closed, if it did that then you knew it still worked. Today with some thermostats, if you do that, you will destroy it as there is a ball of wax which will melt leaving the the thermostat permanently open or closed - can't remember which.
I had "blow back" in my Mazda Protégé after 330,000 Kilometres and after replacing the water pump and the radiator, the mechanic looks at me and says, "oh yeah, if you have blow back, its your head gasket and rings giving you this problem. Don't do anything else until you get a new ring job (I bought a 528i instead)." He gave me the new thermostat he was going to install and said not to install it until after the ring job, if I did, the wax inside would melt when the car heated up too much and I would kill the thermostat - so I drove the car for 6 months without a thermostat.
cars can be driven without thermostats; the only problem you'll face is
A. In winter becomes so hard to get heat into your car. Coolant will be cooled in a wholesale fashion.
B. That little pressure needed for optimum performance will be absent without thermostat.
The immersing the thermostat in boiling water to watch it open then taking it out to see if it closed was the first thing taught to us in auto mechanics in........ 1962.... lol! The next thing we had to do was make out our own gasket with gasket material, hammer, and the part, lightly hammering the edges to form the lines to cut the gasket material... boy am I dating myself...
LOL sounds very innovative THEN. Without History there is no PRESENT; cars included!!
Did you know that car owners (in the past) insisted on living on flat land simply because fuel pumps were not invented yet They relied upon gravity to get their fuel with a top-trunk mounted fuel tanks. Uphill? Can't won't make it. CHEERS
Originally posted by rsn48@Oct 28 2004, 07:07 PM The immersing the thermostat in boiling water to watch it open then taking it out to see if it closed was the first thing taught to us in auto mechanics in........ 1962.... lol! The next thing we had to do was make out our own gasket with gasket material, hammer, and the part, lightly hammering the edges to form the lines to cut the gasket material... boy am I dating myself...
We used to cut them from tin plate and adhere them with halomar blue (a very popular gasket sealent), or just smear loads of halomar blue around the faulty area in the hope it would create a seal. LOL makes me laugh to think of those motorbike heads covered with blue silicone.
unlike most of these people I've worked on these cars for the last 3 years. Unless you have some kind of really unusual problem (which I highly doubt) you probably have a waterpump with a broken impellar. Replace the waterpump and thermostat (t-stat w/ housing) and you will be fine.
To have BMW experts, like you, on the forum is always greatly appreciated.
p.s. What we know is mostly problems we have encountered with our own cars then when it is fixed (dealers,mechanics, experts like you) we try to share the info. with each other hence COMMUNITY FORUM.
I think it is a nobble task to help other people saving their hard earned money knowing BMWs are expensive to maintain. Keep the good work..CHEERS
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